And now, some random speculative ranting! This is just me going off little else but my own imagination, so only read if you're interested.
A Theory on the Knaaren's Origins:
The Leptys planned to make a tough, strong, resilient species. While he has many powers of creation, but he was not in complete mastery of them and was unsure how to go about making this species, especially since they would inevitably share his weakness to the sun. So he made a number of different races and deliberately put them in a harsh, unforgiving desert to test them, pitting them against each other in a 'game' of Natural Selection; survival of the fittest. It was, in essence an experiment to find out what worked and what didn't. The Knnaren were the winners of this 'game', building vast tunnels underground to escape their harsh environment, and who's firceness and toughness allowed them to overpower the other species. The other creatures - failed experiments - were not so lucky, and the collossal skeletons of one such race remain, littered across the desert as a reminder of this.
EDIT: The Knaaren Arena could be a homage to this, pitting people against each other to see who the strongest is.